We have been to Orlando 4x during that approx week, every 3 years. UO crowds were very manageable the 2 trips we did there (2012, 2015). Disney was more crowded (2009, 2018).
Our most recent UO visit was in 2015, less than a year after Diagon Alley opened, and we found it to be very manageable. We stayed offsite, so no EP, but we rode everything we wanted to ride (except MM) multiple times over the course of the week, and were out of the parks by 2pm almost every day. We rode Gringotts with about a 75 min wait on a Sunday evening, and waited about 20 min for FJ. The next longest wait was on our last day, when the guys waited 70 min to ride (BBRB). It was a Friday and it was HOT; everyone wanted to get wet. But most of the rides that day were manageable waits. We didn't do all the roller coasters bc the boys didn't want to go upside down (I love 'em, but they're ride chickens - it was 2018 before I finally got one on a big coaster - he was 16 at the time).
In 2009, it was a very rainy week, so the parks were mostly deserted, even though the rain was mostly light or just drizzle. We just put on ponchos had a great time. Our boys were too young for the big coasters that year, but we did literally everything else and left the parks before dinner both days (we also did Legoland that year). UO in the drizzle is amazing. Short waits and lots of fun.